Dogs May Be Able to Smell Early Cancer

Studies have documented the abilities of dogs to identify chemicals that are diluted as low as parts per trillion. The clinical implications of canine olfaction first came to light in the case report of a dog alerting its owner to the presence of a melanoma by constantly sniffing the skin lesion. Subsequent studies published in major medical journals confirmed the ability of trained dogs to detect both melanomas and bladder cancers.

The new study, led by Michael McCulloch of the Pine Street Foundation in San Anselmo, California, and Tadeusz Jezierski of the Polish Academy of Sciences, Institute of Genetics and Animal Breeding, tested whether dogs can detect cancers only by sniffing the exhaled breath of cancer patients.

In this study, five household dogs were trained within a short 3-week period to detect lung or breast cancer by sniffing the breath of cancer participants. The trial itself was comprised of 86 cancer patients (55 with lung cancer and 31 with breast cancer) and a control sample of 83 healthy patients. All cancer patients had recently been diagnosed with cancer through biopsy-confirmed conventional methods such as a mammogram, or CAT scan and had not yet undergone any chemotherapy treatment.

During the study, the dogs were presented with breath samples from the cancer patients and the controls, captured in a special tube. Dogs were trained to give a positive identification of a cancer patient by sitting or lying down directly in front of a test station containing a cancer patient sample, while ignoring control samples.

The results of the study showed that dogs can detect breast and lung cancer with sensitivity and specificity between 88% and 97%. The researchers concluded that breath analysis has the potential to provide a substantial reduction in the uncertainty currently seen in cancer diagnosis, once further work has been carried out to standardise and expand this methodology.